Eccentric drill tool

ABSTRACT

For use in drilling through earthy material into underlying rock, the eccentric drill tool of the present invention is generally characterized by two cutting portions, with a central portion which is fixed in relation to the drill rod and an eccentric portion which can be shifted between protruding and retracted positions.

[ Aug. 21, 1973 United States Patent Lagerstrom et al. I

1,065,294 6/1913 1,515,819 11/1924 Zublin....

l l ECCENTRIC DRILL TOOL 2/1930 Santiago 9/1930 Akeyson 8/1945 Inventors: Gunnar Lagerstrom, Ektorp; Harry Artur lngvar Wiredal, Sandviken, both of Sweden Assignee: Sandvik Aktienbolag, Sandviken,

Koppl et al. 9/1968 Tiraspolsky et a1... 12/1968 Ahglten 3/1972 Erikson........

Sweden [22] Filed: Nov. 29, 1971 Primary Examiner.lames A. Leppink Attorney-Ralph B. Parker et a1.

[21] Appl. No.: 202,827

[57] ABSTRACT For use in drilling through earthy material into underlying rock, the eccentric drill tool of the present inven- [30] Foreign Application Priority Data Nov. 27, 1970 Sweden.............................

tion is generally characterized by two cutting portions,

26 H n9 Nb n WE 1 C SUt Um HH 55 with a central portion which is fixed in relation to the [58] Field of Search.......................175/258-261, 175/398, 384, 292, 284, 260

drill rod and an eccentric portion which can be shifted between protruding and retracted positions.

9 Claims, 9 Drawing Figures [56] References Cited UNITED STATES PATENTS 1,805,806 5/1931 Cambell et 175/273 PATENTEDAUBZI I975 SHEEP 1 IF 3 1 ECCENTRIC DRILL TOOL This invention relates to the earth-rock drilling art, and is concerned with the provision of an improved eccentric drill tool.

For drilling through earth material into underlying rock, for instance when drilling a well, it previously has been the practice to drive a string of drill rods into the ground together with a surrounding string of easing tubes. When the drilling was finished, the drill rod was extracted while the casing was left in the ground. In order to render this possible the drill bit had to be shiftable between a drilling position, wherein it protruded laterally beyond the casing, and an extraction position, wherein it was laterally contracted and could be withdrawn within the casing tube. Earlier, this shifting has been accomplished by means of a lateral movement of the whole bit.

According to the present invention the drill tool is formed into two cutting portions, to wit, (1) a centric portion that is fixed in relation to the drill rod, and (2) an eccentric portion that is shiftable between a protruding and a retracted position. This formation represents a simplification of the construction in that the size of the shiftable part is relatively small: also, the stresses on the shiftable part are smaller.

The invention will now be described in greater particularity in the following specification taken with the illustrations thereof in the appended drawing wherein:

FIG. 1 is a side view of a first embodiment of the invention, the bit being in drilling position;

FIG. 2 is an end view taken in the direction 22 in FIG. 1;

FIG. 3 is a side view of the same drill with the drill bit in extraction position;

FIG. 4 is a side view partially in section, of a second embodiment of the invention with the drill bit in drilling position;

FIG. 5 is a sectional view on line 5-5 of FIG. 4;

FIG. 6 is a sectional view on line 6-6 of FIG. 4;

FIG. 7 is a side view, partially in section, of a third embodiment with the drill bit in drilling position;

FIG. 8 is an end view along the line 88 of FIG. 7; and

FIG. 9 is a side view, partially in section, of the drill (FIG. 7) in extraction position.

In FIG. 1 the lower portion of the drill rod 10 is shown in side view and the lower portion of the tube casing 11, surrounding the drill rod, is shown in section. The lower end of the drill rod has a thread on which is screwed a bit adapter 12 having a cylindrical upper end 13 which serves to guide the adapter in the tube. There should be a suitable clearance between the guide portion 13 and the tube casing 11 in order to allow flushing medium and cuttings to return from the bit along the inside of the casing tube. The lower end 24 of the adapter 12 is threaded and carries a drill bit 25. The drill rod usually consists of a string of extension rods, coupled by threads, and the tube casing of a similar string of extension tubes.

The intermediate portion 14 of the adapter 12 is cylindrical. It axis 15 is laterally displaced in relation to the drill axis 16. On said portion 14 there is mounted an eccentric sleeve 17 having a cutting insert 18. Sleeve 17 has a projection 19 on its upper side which projection is arranged to abut against a projection on the guide portion 13 when the sleeve is turned on the intermediate portion 14.

When the drill rotates during drilling, the eccentric sleeve 17 is retained by the surrounding earth material so that the drill rotates within said sleeve until the projections abut in a position where the cutting insert 18 protrudes beyond the tube as shown in FIG. 1. When the drill rod is being extracted the drill rod is turned the opposite way. Sleeve 17 is again retained by the surrounding material until the projections 19 and 20 abut from the other direction. The size of the projections is so selected that the rotation is half a turn (180). Due to the displacement of axis 15 of the intermediate portion 14, the cutting portion 18 now lies within the easing tube as shown in FIG. 3 and the rod can be pulled up within said tube.

A central flushing bore 21 has lateral branches 22 and 23 that keep clean the space between eccentric sleeve 17 and intermediate portion 14. A further branch 26 from this space supplies flushing medium to the eccentric cutting insert 18.

The embodiment in FIGS. 4 6 comprises a bit adapter 30 and a casing tube 31. The drill rod itself is not illustrated. The adapter 30 consists of l a guiding top part 32 within the casing tube, (2) an intermediate portion 34 on which is mounted a sleeve 35 with a cutting insert 36, and (3) a threaded bottom part 37 carrying a drill bit 38. In this embodiment the sleeve 35 cannot rotate as in the preceding embodiment but rather it is locked against rotation by flat bevels 39 on the intermediate portion 34 and matching flat surfaces inside the sleeve. The lateral shifting of the sleeve is effected by axial movement of the sleeve along said portion 34. The upper and lower parts of the portion 34 are laterally displaced in relation to each other, so that when the sleeve is in drilling position at the upper end of portion 34, as shown in FIG. 4, the cutting edge 36 protrudes beyond casing tube 31. But when the sleeve is in its extraction position at the lower end of the portion 34, the cutting edge 36 is retracted within casing tube 31.

FIGS. 7 9 illustrate a further embodiment having a rotatable sleeve 42 similar to sleeve 17 shown in FIGS. 1 4. In this case drill bit 40 has an integral shank 41 on which is mounted the rotatable sleeve 42. Shank 41 is coupled to the drill rod by means of a coupling sleeve 43 having threaded bores at both ends.

The rotation position of sleeve 42 is determined by projections 44 and 45 on the sleeve and the bit, respectively. In this case they are positioned on the lower side of the sleeve, which has the advantage that the upper contact surfaces 46 between sleeve 42 and coupling sleeve 43 are plane, thus rendering efficient the transfer of percussion energy to the sleeve 42. The contact surfaces 47 on projections 44 and 45 are in this case inclined, which design has some advantages. The sleeve 42 is urged upwardly against the sleeve 43 thus improving the contact between surfaces 46. Moreover, the bit 40 is constantly held screwed into the sleeve 43. This prevents the bit from unscrewing itself which otherwise may happen when the drill is used for reaming a previously drilled hole and only the eccentric cutting edge 48 is active.

We claim:

1. Eccentric drill tool, for percussion drilling with drill rod means within casing tube means, which comprises two cutting parts, to wit (1) a centric part that the casing tube and serving to limit lateral movement of the tool.

2. Drill tool as defined in claim 1, in which the sleeve is turnable on an eccentric portion of a shank portion of the centric part.

3. Drill tool as defined in claim 1, in which the sleeve is axially movable on a shank of the centric part be tween two portions of said shank that are laterally displaced in relation to each other.

4. Drill tool as defined in claim 1, in which the centric part is a standard drill bit usable for drilling without with the drill bit.

casing tube means.

5. Drill tool as defined in claim 2, in which rotary movement of the sleeve is limited by two axially protruding, sideways abutting projections, one situated on the sleeve and the other fixed on the drill rod.

6. Drill tool as defined in claim 5, in which the projection on the sleeve protrudes forwardly and the other projection is situated on the drill bit and protrudes rearwardly.

7. Drill tool as defined in claim 6, in which the projections have inclined abutting surfaces, the rotation of the drill during drilling exerting a wedging actionbetween the abutting surfaces, urging the sleeve rearwardly against a shoulder on the drill above the sleeve.

8. Drill tool as defined in claim 7, in which the shoulder is formed by the fore end surface of a sleeve serving as the guiding means.

9. Drill tool as defined in claim 2, in which the shank portion, on which the sleeve is joumalled, is integral UNITED STATE PATENT OFFICE CERTIFICATE OF CORRECTEON Patent No. 2 7 R )+7O Dated 5; 21 1913 Inventor(s) It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

[73] Assignees: Sandvik Aktiebolag, Sandviken, Sweden and Atlas Copco Aktiebolag, Nacka5 Sweden Signed and sealed this 19th day of February 19714..

(SEAL) Attest t EDWARD M.FLETCHER,JR

C. MARSHALL DANN Attesting offlcer- Commissioncr f Patents 

1. Eccentric drill tool, for percussion drilling with drill rod means within casing tube means, which comprises two cutting parts, to wit (1) a centric part that is fixed in relation to the drill rod means and (2) an eccentric part, in the form of a sleeve, which eccentric part is shiftable in relation to the drIll rod means between two different positions, in one of the positions said eccentric part protruding laterally in front of the casing tube means whereas in the other of said positions said eccentric part is contracted laterally and retractable within the casing tube means, said tool further comprising a guiding piece acting against the inside of the casing tube and serving to limit lateral movement of the tool.
 2. Drill tool as defined in claim 1, in which the sleeve is turnable on an eccentric portion of a shank portion of the centric part.
 3. Drill tool as defined in claim 1, in which the sleeve is axially movable on a shank of the centric part between two portions of said shank that are laterally displaced in relation to each other.
 4. Drill tool as defined in claim 1, in which the centric part is a standard drill bit usable for drilling without casing tube means.
 5. Drill tool as defined in claim 2, in which rotary movement of the sleeve is limited by two axially protruding, sideways abutting projections, one situated on the sleeve and the other fixed on the drill rod.
 6. Drill tool as defined in claim 5, in which the projection on the sleeve protrudes forwardly and the other projection is situated on the drill bit and protrudes rearwardly.
 7. Drill tool as defined in claim 6, in which the projections have inclined abutting surfaces, the rotation of the drill during drilling exerting a wedging action between the abutting surfaces, urging the sleeve rearwardly against a shoulder on the drill above the sleeve.
 8. Drill tool as defined in claim 7, in which the shoulder is formed by the fore end surface of a sleeve serving as the guiding means.
 9. Drill tool as defined in claim 2, in which the shank portion, on which the sleeve is journalled, is integral with the drill bit. 